In the field of curable elastomeric compositions, base materials are most often provided in slabs, or blocks, of uncured gum base that have a weight of more than 25 kg. This stems from the inability of such base gums to be extruded into pellets because of their inherent stickiness and caking propensity, even at room temperature.
Thus, in order to be compounded into a variety of compositions having certain properties, such blocks of gum base need to be extensively chipped or milled into smaller lumps immediately before processing, which are ram-fed into the blending equipment under the simultaneous addition of fillers and additives. Such blending equipment can often only function batch wise, making the compounding of elastomeric compositions cumbersome and subject to the use of costly chipping and milling machinery.
It would be therefore desirable to provide a non-caking base gum that can be processed as a free-flowing particulate form such as pellets and which can be directly fed into an extruder in a continuous process without the need to previously chip it into smaller lumps.
In addition to their ability to be processed as free-flowing particulates, such base gum compositions preferably also have material properties that at least match the properties of common base gums and allow for the manufacture of highly demanding, at least partially cured, elastomeric compositions for applications experiencing large temperature variations such as in automotive, aerospace, rail and cabling applications.